Lighters of this type have been marketed for many years with a certain commercial success thanks to an ignition that is facilitated in relation to the conventional friction wheel lighters. Indeed, the production of a flame using a wheel lighter requires two movements (rotation of the wheel and pressing on a plunger) from the user, although with a piezoelectric lighter it requires only a pressing movement on a plunger.
Nevertheless, the manufacture of piezoelectric ignition lighters is more complex, not only due to the presence of a piezoelectric generator, but also due to the fact that particular precautions must be taken in order to ensure the ignition of the air/gas mixture. Indeed, the electric arc has an extremely short duration, as well as a limited energy. Therefore, the lighters marketed of this type systematically adopt on the gas outlet nozzle an additional device to the friction wheel lighters. The function of this device on the one hand is to create one or several secondary gas flows and, on the other hand, to constitute a second electrode arranged in a region propitious to the ignition. These secondary gas flows must have a speed and an output flow that are much less than the main flow in order to favor the mixture with the ambient air and attain a proportion that is close to the stoichiometry, between 1 and 8% of gas, making ignition possible. It is widely accepted that such a diffusing device is required in order to obtain a stoichiometric zone that is sufficiently extended for the ignition of a piezoelectric lighter.
In the vast majority of cases, this device is formed by a helical spring with spaced spires of very small diameter and mounted via insertion into the orifice of the gas outlet nozzle. This embodiment is shown in FIG. 4 and described in numerous patents, as for example FR2551535 or EP1435487. A dispensing device carried out by a spring represents an extra cost, but above all the mounting of this spring of small dimensions via insertion into the nozzle complicates the manufacture substantially. During use, it may occur that the spring becomes deformed, or even pulled off of the nozzle, due to the introduction of a foreign body behind the windshield cover.
In order to limit these disadvantages, it has been proposed to realize the diffusing device using a cap mounted on a nozzle having an auxiliary output orifice, as described in U.S. Pat. No. 6,672,861. This solution requires, however, an additional part of small dimensions and a nozzle having an auxiliary orifice, which does not make it possible to directly use the standard nozzles manufactured in very large quantity for the friction wheel lighters.